Deck 25: Microbial Infection and Pathogenesis

Question 1

Staphylococcus aureus produces ________, leading to fibrin clots that protect them from attack by host cells.

A) collagenase
B) coagulase
C) lipase
D) amylase

Answer 1

B

Question 2

The decrease or loss of virulence of a pathogen is referred to as

A) aging.
B) attenuation.
C) disinfectivity.
D) lethal dose.

Answer 2

B

Question 3

Diptheria toxin is a

A) type of endotoxin.
B) cytolytic toxin.
C) AB toxin.
D) superantigen toxin.

Answer 3

C

Question 4

Capsules are particularly important for

A) making bacteria more vulnerable to host defense mechanisms.
B) making bacteria less pathogenic.
C) protecting bacteria from host defense mechanisms.
D) allowing bacteria to become more phagocytic.

Question 5

Pathogenicity is the ability

A) of the host to inflict damage on the pathogen.
B) of the host to resist damage by the pathogen.
C) of the pathogen to inflict damage on the host.
D) None of these are correct.

Question 6

It is thought that attenuation occurs especially in a laboratory setting because

A) nonvirulent or weakly virulent mutants grow faster in laboratory media when there is no selective advantage to virulence.
B) pathogens lose virulence with age and survive longer in laboratory cultures.
C) patients can be treated with drugs that induce attenuation.
D) there is selection for more virulent strains in the laboratory.

Question 7

Compared with an endotoxin, would a bacterial exotoxin generally be more likely to function after it had been significantly heated?

A) Yes, because exotoxins are very heat stable compared to endotoxins.
B) Yes, because exotoxins are proteins and non-living but endotoxins are part of the bacterial cell wall.
C) No, because exotoxins are carbohydrates and endotoxins are proteins.
D) No, because exotoxins are heat-labile and less resistant to heating than endotoxins.

Question 8

An endogenous pyrogen is

A) a chemical from the bacterial cell wall that causes fever.
B) a chemical produced by a host's own immune system that causes fever.
C) a chemical released by a bacterial cell that causes fever.
D) a chemical produced within a bacterial cell that is released during cell division or at death of the bacterium, at which point it causes fever.

Question 9

Decalcification of the tooth enamel is caused by

A) lipopolysaccharide.
B) dextrans.
C) formic acid.
D) lactic acid.

Question 10

Shiga toxin is an enterotoxin that is produced by

A) Shigella dysenteriae.
B) Clostridium tetani.
C) Escherichia coli O157:H7.
D) Vibrio cholerae.

Question 11

The α-toxin of Clostridium perfringens is

A) an endotoxin.
B) an enterotoxin.
C) a lecithinase.
D) a superantigen toxin.

Question 12

Salmonella species use ________ to facilitate attachment to gastrointestinal tissue.

A) type I fimbriae
B) antiphagocytic proteins
C) siderophores
D) pili

Question 13

Which of the following hemolysins is a phospholipase?

A) lecithinase
B) streptolysin-O
C) Staphylococcal α-toxin
D) leukocidin

Question 14

Tetanus toxin causes

A) muscles to be unable to relax.
B) muscles to be unable to contract.
C) severe diarrhea.
D) hemolytic uremic syndrome.

Question 15

Exotoxins are ________, but endotoxins are ________.

A) lipopolysaccharide-lipoprotein complexes / proteins
B) carbohydrates / proteins
C) lipids / proteins
D) proteins / lipopolysaccharide-lipoprotein complexes

Question 16

An outer coat consisting of a dense, well-defined polymer layer surrounding a cell and used in attachment is called a

A) capsule.
B) cytoplasmic membrane.
C) lipopolysaccharide layer.
D) pilus.

Question 17

Staphylococcus aureus and Streptococcus pyogenes strains can produce ________ that cause the severe and sometimes life-threatening symptoms of toxic shock syndrome.

A) endotoxin
B) superantigen toxins
C) AB toxins
D) cytolytic

Question 18

Influenza virus targets

A) respiratory epithelium.
B) gastrointestinal cells.
C) oral cavity cells.
D) throat epithelium.

Question 19

Which of the following is NOT a subunit of lipopolysaccharide (LPS)?

A) O-specific polysaccharide
B) lipid A
C) core polysaccharide
D) M protein

Question 20

The following bacterial genera are all implicated in dental caries EXCEPT

A) Fusobacterium.
B) Borrelia.
C) Streptococcus.
D) Corynebacterium.

Question 21

What is the difference between adherence and colonization?

A) Colonization occurs when transient microbes are on a tissue, whereas adherence is a more permanent attachment to cells.
B) Colonization occurs when microbes begin to spread in host tissues, whereas adherence occurs when microbes initially attach.
C) Colonization occurs when microbes begin to spread in host tissues, whereas adherence occurs when microbes first begin to reproduce in the host tissues.
D) Colonization occurs when a microbe begins to grow in host tissues whereas adherence occurs when the microbe initially attaches.

Question 22

Cytolytic toxins

A) are extracellular proteins.
B) cause cell lysis and death.
C) damage host cytoplasmic membrane.
D) are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

Question 23

Which of the following is a way to prevent attenuation and maintain virulence in a bacterium?

A) laboratory subculture
B) inoculating an animal with the bacterium
C) polymerase chain reaction (PCR)
D) antibiotic therapy

Question 24

Siderophores are

A) molecules that aid directly in attachment to host cells.
B) inorganic molecules that help in active transport.
C) organic molecules that help pathogens take up iron.
D) toxins that affect the gastrointestinal tract.

Question 25

Which disease CANNOT be prevented via the use of a vaccine generated from an attenuated pathogen?

A) malaria
B) measles
C) mumps
D) rubella

Question 26

Epithelial cells lining the respiratory tract form a

A) dry and rigid barrier with tight junctions between cells.
B) impenetrable barrier to infection.
C) mucous membrane.
D) connective tissue layer.

Question 27

Which of the following is an important factor in the development of dental caries?

A) high salt diet
B) high sugar diet
C) high acid diet
D) low salt diet

Question 28

________ in saliva cleaves glycosidic linkages in the peptidoglycan that is present in bacterial cell walls, weakening the wall and potentially causing cell lysis.

A) Mucus
B) Lysozyme
C) Fibrin
D) Lipid A

Question 29

Which genus produces hyaluronidase?

A) Mycobacterium
B) Streptococcus
C) Shigella
D) Procholorococcus

Question 30

Which of the following does NOT affect pathogen growth?

A) availability of microbial nutrients
B) pH
C) temperature
D) All of these answer choices affect growth.

Question 31

Pathogenicity and virulence differ in that

A) pathogenicity refers to the overall ability of a microbe to cause disease, whereas virulence refers to the ability of one microbe to cause disease relative to another.
B) virulence refers to the overall ability of a microbe to cause disease, whereas pathogenicity refers to the ability of one microbe to cause disease relative to another.
C) pathogenicity only refers to pathogens, whereas virulence refers to any microbe that can cause an infection.
D) virulence only refers to pathogens, whereas pathogenicity refers to any microbe that can cause an infection.

Question 32

The spread of pathogens through the blood and lymph systems that results in a bloodborne systemic infection is called

A) bacteremia.
B) cancer.
C) pathogenesis.
D) septicemia.

Question 33

Which of the following pathogens does NOT use capsules or a slime layer for attachment?

A) Vibrio cholera
B) Streptococcus pneumonia
C) Bacillus anthracis
D) All of these pathogens use capsules or slime layers for attachment.

Question 34

________ is a damage or injury to a host organism that impairs its function.

A) Trauma
B) Infection
C) Disease
D) Transmission

Question 35

Which of the following is TRUE about flagella?

A) They are the most important structure in adherence.
B) They are not involved in adherence and colonization at all.
C) They are as important in adherence as pili and fimbriae.
D) They may be involved in adherence to a lesser extent than pili and fimbriae.

Question 36

Which of the following is NOT important for the adherence of bacteria to host tissues?

A) lipopolysaccharides
B) capsule
C) adhesins
D) slime layer

Question 37

Which of the following is a reason that specific pathogens tend to infect specific tissues?

A) Some tissues have receptors for microbes, but others do not.
B) There are chemical and physical differences between tissues.
C) Tissues with neutral pH are colonized but those with acidic or alkaline pH are not.
D) Microbes preferentially target external tissues, such as skin, as the environment is more favorable for their growth than inside the body.

Question 38

Which of the following is NOT an example of an AB toxin?

A) shiga-like toxin
B) hemolysins
C) botulinum toxin
D) tetanus toxin

Question 39

Which of the following is more likely to cause urinary tract infections?

A) fimbriated strains of Escherichia coli
B) non-fimbriated strains of Escherichia coli
C) both fimbriated and non-fimbriated strains of Escherichia coli
D) None of the answers are correct.

Question 40

The collective term for the organisms living on or in the human body, as opposed to a general term for organisms in an environmental habitat, is

A) the human microbiome.
B) the microbiota.
C) transient microbial flora.
D) pathogens.

Question 41

An opportunistic pathogen causes disease ONLY in the presence of normal host resistance.

Question 42

________ are toxic proteins released from the pathogen during normal growth.

A) Endotoxins
B) Exotoxins
C) Macrotoxins
D) Microtoxins

Question 43

Which of the following is a major growth-limiting micronutrient that influences microbial growth?

A) iron
B) water
C) vitamin K
D) sugar

Question 44

________ are microbial infections acquired by hospital patients with noninfectious diseases because they are compromised hosts.

A) Healthcare-associated infections
B) Immunocompromised infections
C) Pathogenic infections
D) Virulent infections

Question 45

The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as

A) Antigen dose₅₀.
B) Virulence-50.
C) LD₅₀ (lethal dose₅₀).
D) Death rate-50.

Question 46

The process by which white blood cells ingest and kill bacteria is called

A) exocytosis.
B) transcription.
C) phagocytosis.
D) translation.

Question 47

Cholera begins following a bite from a mosquito.

Question 48

The condition that results when some bacteria are shed in the bloodstream and distributed to distant parts of the body but do not reproduce in the blood is called

A) septicemia.
B) bacteremia.
C) uremia.
D) erythemia.

Question 49

The best term to describe the general process by which microorganisms cause diseases is known as

A) pathogenesis.
B) virulence.
C) invasion.
D) infection.

Question 50

Virulence refers to the overall ability of an organism to cause disease.

Question 51

Which of the following is a category of exotoxin?

A) cytolytic toxin
B) lipophilic toxin
C) α-toxin
D) β-toxin

Question 52

Attenuated vaccines cause a weaker immune response than killed vaccines.

Question 53

Septicemia is an example of a

A) systemic infection.
B) transient infection.
C) localized infection.
D) autoimmune infection.

Question 54

The macromolecules responsible for bacterial adherence that are NOT covalently attached to bacteria are collectively called

A) lipid A.
B) biofilms.
C) capsules.
D) glycocalyx.

Question 55

Streptococcus mutans produces dextran to aid in attachment to tooth surfaces.

Question 56

Microbes initially colonize teeth by attaching to lipids attached to the enamel.

Question 57

Pathogenicity islands are clusters of genes for virulence factors that are located together on the bacterial chromosome.

Question 58

Streptococcus pneumonia strains with capsules were called smooth because of their appearance on plates.

Question 59

Virulence factors in Salmonella include antiphagocytic proteins.

Question 60

Pathogen virulence NEVER changes throughout a hostʹs life.

Question 61

Vibrio cholerae is a highly virulent pathogen compared with the influenza virus.

Question 62

Diphtheria toxin inactivates elongation factor 2 by catalyzing the attachment of adenosine diphosphate ribose from NAD⁺.

Question 63

Gram-positive bacteria produce endotoxins.

Question 64

Endotoxins are released in large amounts only when cells lyse.

Question 65

It used to be thought that streptococci were the primary bacteria in dental plaque. What do we now know about the composition of dental plaque and how do we know it?

Question 66

Hyaluronidase worsens infection by causing damage to red blood cells.

Question 67

When does an infection become a disease?

Question 68

Why does Neisseria gonorrhea adhere only to mucosal epithelial cells in the genitourinary tract, eye, rectum, and throat?

Question 69

The Limulus amebocyte lysate assay is used to detect endotoxin in clinical samples such as serum or cerebrospinal fluid.

Question 70

R plasmids help prevent the spread of virulence factors.

Question 71

Clostridium botulinum are endospore-forming bacteria normally found in the soil.

Question 72

Because malnutrition can make the immune system weaker, the number of Vibrio cholera cells necessary to produce cholera in an exposed individual is drastically reduced in individuals with substantial malnutrition.

Question 73

Clostridium botulinum cannot produce toxins in improperly preserved foods.

Question 74

HIV infection causes immunosuppression because it causes the destruction of CD4 lymphocytes.

Question 75

Invasion is the ability of a pathogen to enter into host cells or tissues, spread, and cause disease.

Question 76

Explain how diet plays a role in the development of dental caries.

Question 77

Hormones that are produced under stress boost normal immune responses and play a role in stress-mediated disease resistance.

Question 78

The toxic lipopolysaccharides produced by most gram-negative bacteria are called exotoxins.

Question 79

Virulence genes may be located on mobile genetic elements.

Question 80

Design an experiment to determine whether a potential pathogen produces hemolysins.